1. Field of the Invention
In general, the present invention relates to an electrochemical biosensor strip, and in particular, to an electrochemical biosensor strip including a code-recognition element on one end of a back side of a base for avoiding calibration steps by users. The present invention further relates to a method for identifying a corresponding biosensing device, in particular to a method for identifying a corresponding biosensing device by using a ratio of lengths of each length-changeable area of the strip.
2. Description of the Related Art
Since the improvement of science and technology, many test processes operated in hospital in the past may now be operated at home. In market, many disposable biosensor strips are suitable for nonprofessionals to use and can be operated by users at home without pollution issue. The accurate data can be measured when the biosensor strip cooperated with an appropriate meter.
Taking blood glucose detecting technology as an example, the glucose meter becomes one of common POCT, point of care test, health-care devices in both home-care and hospital-care field.
Nowadays, most glucose meters on market are created based on the theory of Amperometric-electrochemistry. After blood glucose reacts with an enzyme at the electrochemical biosensor strip, electrons release during the forward reaction, and therefore the change of the current flow occurs. Then, by using the glucose meter, the change of the current flow is converted into a value of the blood glucose concentration.
Conventional electrochemical biosensor strip has a base, an electrode system, a reaction area and a cover. The electrode system is laid on the base and comprises an anode electrode and a cathode electrode independently and separately electrically disconnecting with each other. An insulating layer is laid down onto one portion of the electrode system, and therefore one portion of the electrode system is exposed. One end of the exposed portion of the anode and cathode electrode respectively forms a working electrode and a reference electrode, while the other end of the exposed portion of the anode and cathode electrode electrically connect with a meter. The reaction area, which is made depending on different design, is laid onto the working electrode and the reference electrode, and the cover is laid onto the reaction area.
After a sample received into the strip, the sample reacts with a material of the reaction area to produce an electrical signal which is then transferred from the working electrode and the reference electrode to the anode electrode and the cathode electrode of the other end. The coupled meter receives the electrical signal and calculates the signal to convert into an analyte concentration and shows on a display.
However, due to conventional electrochemical biosensor strips have been made by batch production, the variables during batch production will cause the variety of the strips from batch to batch, such as the volume of the working electrodes and the reference electrodes, the quantity of the enzyme and so on. All of above reasons will cause inaccurate results. To avoid this problem, producers set a specific set of calibration code corresponding to the strips per batch to confirm the consistency of the analyzing value before they sell the meters and the strips. The function of calibration in glucose meters is to confirm that the result will not be affected due to different batch of strips.
Main code-calibration methods have been used on market, such as chip-setting method, strip-number comparing method and so on. Take chip-setting method for example. A provided chip must be used to calibrate the code in the glucose meter before the strip inserting to. However, patients often forget to use the chip to calibrate the code, and then cause an inaccurate result. Such method is similar to the disclosure in U.S. application No. 2003204313. The strip-number comparing method described in U.S. Pat. No. 7,514,040 discloses a biosensing meter which not only stores sets of calibration code therein but also receives a code card to store new parameter or downloads new parameter from an internet. One set of the calibration code matched to the batch of the strips must be selected out before users doing the measuring process.
As described above, no matter what kind of code-calibration methods used in glucose meter, all of above must be needed extra calibration steps carried out by users. These cause the complexity during the measuring procedure. Once users do not do the calibration steps correctly, they won't get the accurate results.
Therefore, how to simplify code-calibration steps before measurement and still maintain the accurate results becomes an issue to the producers.
Besides, to ensure that users can use the electrochemical biosensor strips correctly, different strips are usually specific to their own corresponding biosensing device respectively. In other word, biosensing device can carry out the measuring process only when the specific strip insert into the corresponding biosensing device.
Producers in designing electrochemical biosensor strips need to produce varieties of electrochemical biosensor strips due to different purposes, analytes, costumers, or users to meet the market's need, and therefore, kinds of strips and biosensing devices are produced on market. The variety and the complexity of strips and devices are increasing. Hence, how to identify a biosensing device corresponding to a specific electrochemical biosensor strip effectively and simply also becomes an issue for producers and users.